Borussia Dortmund chief executive Hans-Joachim Watzke has thanked Bayern Munich counterpart Karl-Heinz Rummenigge for letting Mats Hummels return to Signal Iduna Park.

The Germany international is back at Dortmund for a second spell after a €38million agreement was reached between the Bundesliga rivals in June.

Hummels won three successive top-flight crowns with Bayern, including last season's when finishing two points in front of BVB, but Rummenigge was still willing to sanction the experienced centre-back's exit when a big bid came in.

"I am very grateful to Karl-Heinz Rummenigge for having respected the player's will," Watzke told DPA. "I thought that was extraordinary.

"The way in which these negotiations ended was an indication to me how respectfully we are working together at the highest levels."

Hummels is not the first player to return to Dortmund in recent years, with Nuri Sahin, Shinji Kagawa and Mario Gotze also being brought back.

Sahin and Kagawa struggled to make much of an impact on their second coming, while Gotze has had a mixed spell since rejoining from Bayern in 2016, but Watzke insisted that this latest case is different to the others.

"Nuri, Shinji and Mario struggled at their new clubs," he said.

"Mats was an absolute star player at Bayern, who won three championships there in three years and was recently voted the strongest centre-back in the league."